Semiconductor devices such as memory devices reside in many computers and electronic products to store data. A typical semiconductor device has many layers of different materials formed on a semiconductor wafer.
During manufacturing, the layers go through many processes. For example, a patterning process puts patterns on the layers. Some patterning processes use a mask to transfer patterns from the mask to the layers underneath the mask. The patterns on the mask itself are often created using a top layer above the mask.
During the patterning process, the material of the top layer may affect the properties of the layers underneath the top layer and the mask. Some conventional top layers are made of oxide material. In some cases, an oxide top layer affects the layers underneath the top layer and the mask. Thus, in some cases, the top layer made of oxide is not suitable.